Eaton EDR-5000, Инструкция по установке, эксплуатации и обслуживанию, Страница: 37 / 1017

EDR-5000 IM02602007E
TI X- Standard Phase and Ground Current Measuring Input Card
A current measuring card is provided with four (4) current measuring inputs: three for measuring the phase currents and
one for measuring of the ground current.
Each of the current measuring inputs has a measuring input for 1 A and 5 A.
The input for ground current measuring either can be connected to a zero sequence current transformer or,
alternatively, it is possible to connect the summation current path of the phase current transformer to this input (residual
connection).
Current transformers have to be earth grounded on their secondary side.
Interrupting the secondary circuits of current transformers causes hazardous
voltages.
The secondary side of the current transformers have to be short circuited
before the current circuit to the device is opened.
The current measuring inputs may exclusively be connected to current
measuring transformers (with galvanic separation).
Do not mix the inputs (1 A/5 A).
Make sure the transformer ratios and the power of the CTs are correctly
rated. If the rating of the CTs is not correct (overrated), then the normal
operational conditions may not be recognized. The pickup value of the
measuring unit amounts to approximately 3% of the rated current of the
device. Also, the CTs need a current greater than approximately 3% of
the rated current to ensure sufficient accuracy.
Example: For a 600 A CT (primary current), any currents below 18 A
cannot be detected.
Overloading can result in destruction of the measuring inputs or faulty
signals. Overloading means that, in case of a short circuit, the current
carrying capacity of the measuring inputs could be exceeded.
Make sure that the tightening torque is 17.7 In-lb [2 Nm].
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